Safety joint for well swabs



2 SHEETS-SHEET 1 mm m X R E 5 e m a I I II I II I/ ATTORNEY Oct. 23, 1951 J. E. REDPATH I SAFETY JOINT FOR WELL SWABS Filed Jan. 15, 1949 L I 7 II n I1 I .1. E. REDPATH SAFETY JOINT FOR WELL SWABS Oct. 23, 195] 2 SHEETSSHEET 2 Filed Jan. 15, 1949 INVENTOR,

42 AM a? m ATTORNEY Patented Oct. 23, 1951 UNITED STATES PATENT OFFICE SAFETY JOINT FOR WELL swans Mi. E. Redplth, Oklahoma City, on

Appl cation January 13, 1949, Serial No. 70,668

8 Claims. (01. 103-202) The present invention relates to well swabs, and more particularly to means for preventing fluid over-load.

Conventional well swabs usually consist of a tubate body having an exterior annular element of rubber which is adapted to contact and seal against the well casing. The body also includes a downwardly closing check valve which remains open when the swab is lowered into the casing through a column of well fluid, and which closes when the body is pulled upwardly.

In swabbing wells with such a swab, the swab is lowered into the casing on a wire line. Should the swab be lowered to an excessive depth below the top of the fluid column, the line often-becomes overloaded to the extent that it is pulled in two when an attempt is made to raise the swab.

The prime object of the present invention is to provide a safety device which may be installed above a usual swab, and which when overloaded, releases fiuid flow through the swab body.

Another object is to provide a safety device which contains its own check-valve, so that the check-valve in the swab may be eliminated.

A further object is to provide a device of this class in which the fluid pressure at which the passage is opened, may be positively and accurately controlled.

The device includes shear-pins for releasing the fluid load when an overload occurs.

Other objects will be apparent from the following description when taken in conjunction with the accompanying two sheets of drawings, wherein:

Figure 1 is an elevational sectional view taken along the longitudinal axis of the tool, the dotted lines illustrating a fragment of the upper end of a well swab, the tool parts being shown in their normal or flow preventing positions;

Figure 2 is a similar view showing the tool parts in open or flow permitting positions;

Figure 3 is a transverse sectional view taken substantially along the line 3-3 of Fig. 1;

Figure 4 is a similar view taken substantially 2 the device of the present invention, but is the device above which the tool of the present invention is adapted to function.

The device of the present invention, per se, includes a tubular body l0 having an axial bore which is separated into upper and lower compartments l I and I2 by a set of radially spaced inwardly projecting vanes l3 having interstices or slots I4 therebetween.

Communicating with the upper chamber H, is a plurality of lateral ports l5 which extend through the annular wall of the body H0.

The lower portion of the body H) has a reduced bore 86 extending axially from the lower end ii of the chamber 82 to the lower end of the body.

Exteriorly, the lowermost end portion of the body is formed into an exteriorly threaded pin 58 by whichthe body may be rigidly yet removably attachedto the upper end of the swab i.

The device further includes an elongated valve member or shuttle which is indicated, as a whole, by the reference numeral 20. The member 20 consists substantially of an upper exteriorly threaded pin 2! formed above a cylindrical head 22 which has a reduced exteriorly cylindrical portion 23 therebelow. The upper portion of the pin portion 28 is solid, except for a transverse port 24 which extends through the pin adjacent its lower end. Below the port 24, the head 22 and the depending portion 23 are provided with an axial bore 25, the lower end of which is reduced in diameter and is formed to provide a seat 26 for a ball valve 21. A stop 40 is provided in said bore 25 above the seat 26.

The depending portion 23 of the member 20 has a groove surrounding its lower portion, and the groove is adapted to nest an annular packing member 28 which is made of some suitable resilient material such as rubber. The packing member 23 has a sealing fit with the wall of the chamber II, and the portion 23 has a working flt with said wall.

Below and integral with the lower end of the depending portion 23, there is provided a tubular stem 29 which has a working fit with the inner edges of the vanes I3. The stem 23 has an axial bore 33 which extends from the seat 26 throughout the entire length of the stem. The lower portion of the stem 23 has a plurality of outwardly extending ribs 3| which are radially spaced to provide slots 32 therebetween. The ribs 3| reside within the lower chamber l2, and together act as a guide for the stem and portion 23.

Although not so shown in the drawings, the stem 23 will be divided laterally through its of the stem 23 working through the vanes 13 of the body It.

When assembled for operative installation, the valve member is moved to the lower end of its travel, and the wall of the body I3 and one of thevanes 3| are laterally bored to receive a shearpin 33. The pin is driven in place; and acts normally to hold the valve 20 against movement in the body l0.

when the valve member is thus held at the lower end of its stroke, the ports l5 are closed by the depending portion 23 thereof. The sealing element 28 then resides below the ports i5 (Fig. 1). During the bailing operation, theball valve 21 seats upon the seat 23 when the device and the swab are being raised in the well casing, and when they are lowered through the fluid column in the well casing, the ball is raised off its seat by the fluid passing upwardly through the bore 2 of the swab, the bore 16 of the pin IS, the chamber [2, the bore 30 of the stem 29, the seat 26, the bore 25 of the depending portion 23, and outwardly through the lateral ports 24.

Should a fluid load in excess of the shear resistance of the pin 33 be placed upon the device, upward pull on the valve member will cause the pin to'be sheared.

When this occurs, the valve member will be lifted tothe upper end of its travel, or to the position illustrated in Fig. 2.

When the valve member 20 reaches the upper end of its permitted travel, the lower end of the depending portion 23 resides in the chamber ll above the lateral ports l5. Well fluid is then free to enter the ports l5 and to flow downwardly in thebody III by passing through the upper chamber II, the slots ll, the slots 32 in the low- .er end of the stem 29, the lower chamber l2, and

the bore l6 therebelow. The fluid may thereafter enter the bore 2 of the the swab and flow therethrough back to the well casing.

After the pin 33 is once stripped, it may be drilled out and replaced so as 10 again put the device into condition for operation.

The pin 2| at the upper end of the body I0 is provided for the purpose of connecting the device to a conventional rope socket, 35 on the lower end of a wire line 36 whereby the tool and swa may be operated.

It is pointed out that any desired plurality of the pins 33 may well be provided so as to properly regulate the shear resistance, or in other words, so as to properly regulate the load lifting capacity of the device. All lifting load which may be borne by the swab, is carried by the shear pin or pins.

Obviously the invention is susceptible to some change or alteration without defeating its practicability, and I therefore do not wish to be conflned to the preferred embodiment shown in the drawings and described therein, further than I am limited by the scope of the appended claims.

including: a body which is tubular throughout its length, said body having lateral ports extending outwardly from its bore, and the lower end of said body adapted to be attached to the upper end of a tubular well tool to form a continuation thereof; a tubular plunger-type valve member slidable in said bore to open and close said ports; a valve seat in the bore of said member; a downwardly closing valve for seating upon said seat; shear pin means for holding said member in position to close said ports; and means for attaching the upper end of said member to a lifting line. 1

2. Structure as specified in claim 1, "in which the valve member has a lower guide portion which is longitudinally fluted to permit downward flow of fluid through the body when the member is raised above the ports.

3. Structure as specified in claim 1, in which a portion of the body wall is longitudinally fluted below said ports, to permit downward flow of fluid through the body when the member is raised above the ports.

4. Structure as specified in claim 1, in which the upper portion of the valve member has lateral passages extending from its periphery to its bore for admitting well fluid to said bore.

5. Structure as specified in claim 1, and an annular sealing element of'resilient material surrounding the valve member for sealing with the wall of said body.

6. An overload safety device for well tools including: a tubular body having a longitudinally fluted annular restriction in its bore for dividing the same into an upper and a lower compartment; lateral ports through the wall of said body adjacent its upper end; means carried by the lower end of said body for coupling it to the upper end of a tubular well tool; a tubular plunger-type valve member having an exteriorly smooth cylindrical portion slidably disposed in the upper chamber of said body for closing and opening said ports; an exteriorly smooth stem portion depending from said cylindrical portion and passing downwardly through said fluted restriction into the lower chamber; radially spaced longitudinally extending guide vanes surrounding and integral with the portion of the stem which resides in the lower body chamber; lateral passages through the wall of said valve member adjacent the upper end thereof for admitting well fluid to the bore of said member; a valve seat formed in the bore of the cylindrical portion of said valve member to admit well fluid to said bore; a valve seat in the bore of said cylindrical portion of the valve member; a downwardly closing valve in said bore for seating upon said seat; means for attaching the upper end of said valve member to a swab line; and frangible pin means attaching said valve member to said body in position to close said lateral parts.

JAMES E. REDPATH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,472,487 Murray Oct. 30, 1923 2,442,642 Eckel June 1, 1948 

